This research proposal deals with the continued investigation of the hemoglobinopathies and thalassemia on a molecular level. It will concentrate on four areas: (1) Continued development of approaches to prenatal diagnosis for Beta thalassemia by DNA analysis. During the past few years, direct methods of prenatal diagnosis of Alpha thalassemia and sickle cell anemia by DNA analysis have become available. The molecular lesions responsible for Beta thalassemia are diverse and it is therefore important to determine the type of mutation present in a given area. With this knowledge, specific methods of prenatal diagnosis could be designed. The implementation of diagnosis by DNA analysis will improve the safety and accuracy of the test. (2) The molecular lesions causing the thalassemia mutations will continue to be characterized. Such studies may further our understanding of the control of globin gene expression. Unidentified Beta thalassemia genes obtained from the work in (1) will be characterized. Interesting mutations which may provide insight into the control of globin synthesis, and spontaneous mutations will also be studied. (3) The transgenic mouse model will be used to study regulation of human globin gene expression. This model may provide a means for studying tissue-specific and developmental controls of human globin gene expression. (4) The use of suppressor tRNAs as a means of overcoming the nonsense mutation in Beta thalassemia will be investigated. Human suppressor tRNA genes that insert lysine or glutamine into the UAG codon will be introduced into erythroid cells from patients with the Beta17 nonsense and Beta39 nonsense mutations.